Brake



March 12, v1946. o. RA sMussEN BRAKE Filed Sept. 23, 1944 INVENTOR (9Za/ flzsmwsezz Patented Mar. 2, 1946 2,396,387

BRAKE Olai' Rasmussen, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application September 23, 1944, Serial No. 555,485

Claims.

A novel brake shoe assembly for vehicles is the subject matter of this invention.

A major object is to provide an assembly of shoes in which a complete servo action is present for both forward and rearward vehicle travel.

A further object is to make sure that the arcuate surfaces of each of the shoes fits the drum during braking.

Other objects including simplicity in construction and a comparatively inexpensive manufacturing cost as will be understood from the description which follows.

In the drawing:

Fig. 1 is a vertical section through the drum.

Fzig. 2 is a section as indicated on Fig. l by line 2- Similarly, lines 3-3 on Fig. 1 show the plane of the other sectional view, Fig. 3.

Referring by reference characters to the several figures, a conventional drum is identified by numeral 5. A cover plate I is fastened as usual to the rigid axle, not shown, by fastening means extending through openings 9. This cover plate carries a shoe anchor represented as a whole by numeral H and an applying means in the form of the conventional wheel cylinder |3of a 'hydraulic brake applying system, From 'opposite ends of the wheel cylinder extend piston rods IE to engage the brakin members. The brake anchor takes the form of a pair of abutment members ll, ll. They have shoulders l9, l9 to engage the adjacent ends of levers 2|, 23. A wedge 25 fits angular faces 21 on the abutments. Into the wedge is threaded an adjusting bolt 21' extending through a sleeve 29, and through the cover plate I and the reinforcing plates 3|. Rotation of the bolt 21' reciprocates the wedge and spreads apart the abutments ll, II to take up for brake shoe wear. On either side of the adjusting nut 21 are securing bolts 33 extendin through slots in the cover plate I and the reinforcing plates 3| and threaded into the abutments to hold the latter in adjusted position relative to the cover plate 1.

The levers 2i and 23 are not brake shoes. They carry the brake shoes. At an intermediate point 35 of lever 2| is pivoted a brake shoe 31 at an intermediate point of the latter. In a similar manner a pivot pin 39' connects intermediate points of lever 23 and shoe 39. Link means 4| connect the lower end of lever 2| at 40 to the lower end of shoe 39 at 38. Link means 43 connect the lower end of lever 23 at 42 to a point 36 near the lower end of shoe 31.

hand. A manually operable lever 45 is pivoted at 41 to the upper end of lever 23. A strut 49 engages an intermediate point of lever 45 and extends to and engages lever 2|. To hold the parts of the manually operable device engaged when the brake is applied hydraulically there may be used a spring 5| in the relation shown. A spring In applying the brake by hydraulic means, fluid medium within the wheel cylinder l3 forces outwardly the rods I5. If it be assumed that the drum is rotating counterclockwise, lever 2| first rotates about its pivotal connection 40 with link Provision is made for applying the brake by means 4| thus carrying shoe 3! into contact with the drum. Thereupon both lever 2| and shoe 31 travel with the drum and the links 4| and 43 force lever 23 and shoe 39 toward the drum and shoe 39 into drum contact. Lever 23 anchor on its abutment l1 and thus both shoes cooperate in resisting drum rotation. Should the drum be rotating clockwise, the action is reversed and both shoes resist drum rotation, lever 2| being anchored on its abutment IT. The same brake action may be effected by the emergency lever acting through the instrumentality of lever 45. In general the emergency application wil be used only on the brakes of the rear wheels while the service application by means of the hydraulic cylinders will be made available for all wheels, front and rear.

When the brake is released the releasing spring 53 holds the levers on the abutments l1 and I1 and also pulls the levers so that the pistons l5 are in their inner stopped position. Under these circumstances the lower end of each lever functions through its link means to push the lower end of the shoe associated with the other lever to an outer limit position short of contact with the drum. Obviously since the action is positive and limited the upper ends of the shoes are swung inwardly away from the drum to a, predetermined extent.

When the levers 2| and 23 are spread apart by the adjusting means at 25 the pivoted connections 35 and 39' between the shoes and levers are moved outwardly so as to bring the midpoints of the shoes nearer the drum, but since the lower ends of levers remain substantially unchanged the link means 4| and 43 serve as before to swing the shoes about their pivots with the levers to a predetermined extent and prevent any dressing or either end 0! the shoes.

I claim:

1. In a brake. a drum, a pair of associated levers floating within said drum, means to spread said levers, anchor means between one pair of adjacent ends of said levers, a shoe pivoted at an intermediate point thereof to an intermediate point of each oi said levers and link means connecting the other end of each lever to an adjacent end of the shoe carried by the associated lever.

2. The invention defined by claim 1, said anchor means being adjustable whereby the pivots between the shoes and levers are movable toward and from the drum.

release position of spreading means whereby the lillilk means functions to prevent dressing or the s oes.

4. In a brake, a drum having an internal circular friction suriace, first and second associated levers positioned within said friction surface, anchor means between a first pair or adjacent ends of said levers, a shoe pivoted at an intermediate point thereof to an intermediate point of each of said levers, means to spread saidelevers radially within said anchor means, the ends of said shoes adjacent said spreading means being unattached, link means connecting the other end of each lever to an adjacent end of the shoe carried by the associated lever, together with yielding means operable to hold said levers against the anchor means.

5. The invention defined by claim 4, said anchor means comprising spaced abutments one for each lever and adjustable wedging means between OLAF RASMUSBEN.

20 said abutments. 

